1. Field of the Invention
The invention relates to a method for testing a dynamic torque generating device on a test bench, particularly an internal combustion engine on the engine test bench, including an adjustable dynamic rotating mechanism serving as driving or loading mechanism connected to a torque generating device by a driving shaft. The invention relates furthermore to a device for determining the dynamic behavior of a driving shaft on a test bench and to test a dynamic torque generating device using an adjustable dynamic rotating mechanism serving as a torque source or a torque sink rotationally connected to both sides or at least to one side of the driving shaft.
2. The Prior Art
Correspondingly dynamic or highly dynamic adjustable rotating mechanisms, such as electric motors, hydraulic engines or the like are currently used as driving or loading mechanisms for the most realistic testing of dynamic torque generating devices such as an internal combustion engine provided as a driving motor for a motor vehicle, for example, whereby said driving or loading mechanisms are in most cases not connected directly to the torque generating device to be tested but they are connected by means of a driving shaft. Dynamic loads develop in the torque transmission elements and they are effective between the respective torque source and torque sink, which can reach undesirable or even inadmissible values based on the occurring torque event and the adjustment of the entire system. To avoid this and possible damages resulting thereby, the driving shafts are up to now designed having a well defined stiffness and damping characteristic allowing certainly a reliable operation of the test bench whereby the corresponding values are selected based on the existing geometric conditions and the material in use. Higher stiffness and lower damping characteristic result basically in lower losses and higher dynamics; however, they demand higher requirements in test bench adjustment.
In the above mentioned driving and loading mechanism, the coupling through the driving shaft determines directly in which way the loading and driving mechanism can influence the dynamics of the entire system and thereby also the torque generating device to be tested. Since the torque generating device can usually not be described through a linear system, the entire system can also not be described simply as a linear system. Irregularities in friction in the torque generating device must be included in the evaluation as a substantial interference which makes the determination of the relevant parameters of a driving shaft considerably more difficult. According to current traditional standards, the actual characteristics of the driving shaft are measured in the disassembled condition and the corresponding parameters are fed into the operational or adjustment system of the test bench to make possible the correct operation of the driving and loading mechanism without the above-described risks. This method has basically the disadvantage that in the real assembly there are always differences between the measured or theoretically calculated parameters and the actual and therefore relevant parameters of the driving shaft—partly because of the installation and partly because of wear or defects, which can occur later or which can occur in varied ways.
The present invention is based on the fact that accurate and current information can be considerably improved relative to the substantial parameters of the torque transmission path influencing the dynamics, particularly in the driving shaft, including the adjustment quality of the test bench as well as monitoring of the dynamic loads. If the corresponding parameters are known only vaguely, then the adjustment parameters must be set with much more care—or, moreover, if changes in relative parameters are observed during the test bench operation or at least before the start of a specific test phase, then a defect on the driving shaft or on the mounting can be detected or even predicted. Realistic and current monitoring of the relevant parameters could be used as an indicator of increasing wear or faulty measuring. The object of the invention is therefore to obtain information of this type.